WP

It argues that WP Engine mentions WordPress in its marketing tools to help sell its product - and therefore should pay to use the trademark.

The trademarks do not cover the "WP" abbreviation, but the WordPress Foundation says: "please don’t use it in a way that confuses people".

It claims Automattic told WP Engine they would have to pay "tens of millions of dollars" in order to continue using the WordPress trademarks.

"We vehemently deny WP Engine’s allegations - which are gross mischaracterizations of reality," it said in a statement, adding that it would "vigorously litigate against this absurd filing".

People like Tricia Fox, who uses a WP Engine subsidiary to host the websites her company serves.